Kelty Cosmic Down 20 Sleeping Bag Review

It's a $100 DOWN bag. Too good to be true? You may be surprised...

Overall Rating: Recommended

The Cosmic Down 20 is a surprisingly well-made down sleeping bag for the price ($109.95), easily comparable to many down bags twice the cost. To be clear, at slightly over 2.5 pounds, this is not what some would consider an ultralight bag, but it is an excellent value with respectable weight and performance. The loft of the bag has a lumpy and uneven look, but the bag insulates well even when the mercury drops to 20 F / -7 C. It would be nice if the hood area were redesigned to optimize loft and sealing, and the draft collar could use a little tweaking. For those people on a budget, this bag is “Highly Recommended.” It’s an exceptional, well-performing sleeping bag, especially at this price point. You could buy a bag that weighs a pound less and lofts better, but it would cost you roughly three times as much.

Introduction

First thing first: It’s a $100.00 DOWN sleeping bag.

A hundred bucks for a down bag?! The skeptic in my head immediately said “Yeah, it’ll weigh five pounds and be good for 60 F (16 C).” But the sleeping bag only weighs two and a half pounds, and it’s been EN tested for 20 F / -7 C. Well, that clinched my curiosity. Is the Kelty Cosmic Down 20 a true bargain, or should backpackers on a budget save for a more expensive bag?

In this overview of the Cosmic Down 20, you can clearly see the over-stuffed nature of some baffles... and the average to under-filled look of a few other baffles. Does the lumpy appearance belie the bag's performance?

The Lowdown

I guess you could say I went into this evaluation with high hopes and low expectations. I’m accustomed to sleeping bags more in the price range of $400, and while the idea of saving $300 was awesome, I didn’t really think the Cosmic Down 20 would keep me warm. How could it? It weighs maybe 12 to 16 ounces more than a bag that costs nearly four times as much... and the Cosmic Down 20 is only using 550 fill down! For such a cheap bag, could the shell material really be light enough to offset the extra weight of 550 fill? As I waited for what I was sure would be an overweight package, I psyched myself up for some very cold nights.

The box that arrived at my doorstep was surprisingly small and light. “Huh,” I thought. “That actually feels about right.” Out of the box and onto the scale: my size regular Cosmic Down 20 weighs 2 pounds 9.6 ounces, 1.6 ounces over spec, but hey, that’s still pretty good. I had imagined wrestling a behemoth into a stuff sack, but it easily stuffed into a 10 liter dry sack. “Huh,” I thought again. “This thing might actually be legitimate.” I shook my head. “Nah, it won’t loft for beans.”

I’m not gonna lie: It isn’t a sexy bag. The 50 denier polyester taffeta shell fabric is not inspiring. The loft of the sleeping bag is... not bad. It does not have the distinctly reassuring appearance of, say, Western Mountaineering bags and their slightly overstuffed baffles. Maybe it looks a little lumpy? But the Cosmic Down 20 lofts well enough, even better than many. Down distribution in the baffles is more adequate than some $200 down bags I’ve handled. There are definitely some thinner spots in loft, particularly on the bottom of the bag, but overall I’m pretty pleased.

Brand

Model

Temperature Rating (F / C)

Down Rating

Length (ft / m)

Shoulder Measurement (in / cm)

Fill Weight (oz / g)

Total Weight

Cost

Cost per Ounce

Kelty

Cosmic Down 20

20 / -7

550

6.0 / 1.8

62.0 / 157.5

20.0 / 567

2 lb 8 oz / 1.13 kg

$109.95

$2.75

Western Mountaineering

Ultralite

20 / -7

850

6.0 / 1.8

59.0 / 149.9

16.0 / 453.6

1 lb 13 oz / 0.82 kg

$385.00

$13.28

Just for grins, a comparison shot of the Cosmic Down 20 alongside a Western Mountaineering Ultralite. Note the hood and shoulder region “tummy tuck” on the CD 20; I wish there were more down in this region.

The hood has a reasonable amount of depth and shape, and has been cut to allow a bit of an insulated ruff around the top of the opening. Although I can fluff the hood to get some more down into the area, the neck region of the hood habitually shifts down out of the neck region and toward the head. The bag should really have some more down in that area, or use an additional baffle. There is a passive top draft collar in the Cosmic Down 20, an insulated tube that hangs from the top of the bag to block air movement. The draft tube is not circumferential, nor can you cinch it down, but the passive top collar does help keep the bag warmer.

The zipper draft tube is surprisingly well filled, and the zipper runs freely. The Cosmic Down 20 uses a three-quarter-length zipper, but it’s a three-quarter-length zipper that I’ve found eminently functional. Most partial zips don’t go down far enough to be useful for venting, but this one hits me just below the knee. They could have extended the zipper another foot for about an ounce, but oh well.

The three-quarter-length zipper has proven to be a true three-quarter-length zipper... it seems like many companies' “three-quarter zips” are closer to half zips to me. You can also get a slightly different perspective on loft here.

There are two large loops sewn onto the footbox for hanging, and a number of small loops along the sides so you could secure a pad underneath the bag. I’ve never found the need to do that, but they’re there if you’re so inclined.

Now that you’ve had the full tour, let’s take a look at some real-world performance. Does the bag do what it’s supposed to do?

Performance

I’m not a huge fan of equipment surprises when I’m in the backcountry, so I first test almost all new equipment in the backyard. Walking from my back door to the tent on a night in the high 30s I shivered a little, and thought to myself that I’d probably be headed back for the house halfway through the night. Instead I woke up warm, cozy, and smiling somewhat late the next morning. Huh! Yet another pleasant surprise from the Cosmic Down 20.

That’s not to say I trusted the rating yet, but the bag kept me warm on progressively cooler nights, including one that dipped into the twenties. The forecast for an upcoming weekend trip was for lows in the teens; I considered bringing a different sleeping bag, but decided to just bring an extra down layer and warmer pants to complement the Cosmic Down 20 if needed. Despite temps bottoming out in the low twenties, I slept warm and cozy for that weekend and the next. A night in the hammock (with a DownMat under me) down to the mid twenties found me, yet again, warm and toasty.

I’ve found that using pads with barely adequate insulation can dramatically decrease the performance of a bag, therefore I used pads with R-values ranging from 5 to 8 (yeah, I know the 8 is high, but I have the pad, it’s comfy, and I love it) for all my field evaluations. Although I normally roll over with the bag (kind of wearing it as I roll over to sleep on my side), I found myself turning inside the Cosmic Down 20 to keep the bottom surface down. I didn’t have much faith in the ability of its underside insulation.

Note the passive top collar and draft collar of the Cosmic Down 20. No, they’re not of the same quality as a WM bag, but the build construction is much, much higher than what I’ve seen in other bags near this price range.

A late fall/early winter overnighter was forecasted with single-digit temperatures. Although I was game to experiment and had gained healthy respect for the Cosmic Down 20, I took along a 0 F / -18 C bag as a backup. That night only dropped to about 15 F / -9 C, but I woke up perhaps five hours into the night, feeling particularly cold. I didn’t want to start from scratch warming up the zero degree bag, so I pulled it over me quilt-style and hunkered down for the rest of the night. It wasn’t until that morning when I got up and moved around for awhile that I really warmed up.

I was a bit perplexed. That night wasn’t significantly colder than several others, when I had been warm using the same pad and clothing combo. At first I dismissed it as a fluke, perhaps a hydration problem I wasn’t aware of, maybe a slight cold, or a light dinner... but all factors struck me as being completely normal. Then I realized that what had changed wasn’t so much the low temperature, but the high temperature of the day.

My previous experiences with the bag had all been during warm days, with highs perhaps in the forties and bottoming out in the twenties in the middle of the night. The night I slept cold had been in the mid twenties all day and dropped even lower that night. I had essentially been coasting through the previous lows on the borrowed heat of the day.

Night falls, but the loft of the bag is relatively inspiring. I gotta say, the shell doesn’t look too bad under flash light.

If I were headed on a trip and expected a narrow range of temperature variation, hovering around 20 F / -7 C, the Cosmic Down 20 isn’t the bag I would take. However, if I were looking for a decent three-season bag and typical temperature swing, this bag could be a good choice. Trips with days in the 40s or 50s F and nights in the 20s or 30s F would be fine with the Cosmic Down 20, and frankly those are conditions most backpackers are more likely to encounter.

Conclusion

The real question, then, “Should everyone buy this bag?”

No.

If you’re counting ounces, you could save three-quarters of a pound by going to an 850-fill bag. If you want and expect greatness from your equipment, this isn’t your bag. The Cosmic Down 20 is for those seeking a serviceable sleeping bag that gets pretty small, is reasonably light, and will do the trick for most three-season conditions. I see the bag working particularly well for those who would benefit from other gear upgrades... perhaps the $300 “savings” of the Cosmic D could be put toward a new backpack or tent that would save a few pounds.

Who should buy the Cosmic Down 20? Anyone on a limited budget who’s in the market for a good all ‘round sleeping bag. If someone’s new to backpacking and trying to put together their whole kit, this sleeping bag is a good bargain. Note that when I say “bargain,” I don’t mean cheap... I mean a good value. College students or Scouts might want to take a look at the Cosmic Down 20. If you want a spare bag, or even if you’ll be spending more time afield, this would be a durable option for the same price as value-priced synthetic bags. If someone wants to get into backpacking, but doesn’t want to make a large equipment investment, this bag could be just the ticket. There is nothing outwardly impressive about this bag in appearance, but it works. It’s a much better sleeping bag than I imagined.

Disclosure: The manufacturer provided this product to the author and/or Backpacking Light at no charge, and it is owned by the author/BPL. The author/Backpacking Light has no obligation to review this product to the manufacturer under the terms of this agreement.

Thank you for the review and specifically for using English and metric units. Although I agree that metric is better, I don't think that way, and want to scream every time I read a Roger Caffin article where I need to convert.

To compare the loft of the bags, a useful calculation is to multiply the fill rating by the fill amount:

Just thought I would point out that Campmor has these in regular length for $80 right now: http://www.campmor.com/kelty-cosmic-20-degree-sleeping-bag-regular-1.shtml?source=CI&ci_src=14110944&ci_sku=41952

I got one of these to try out last summer for $90 from Target. I put in a few summer trips with it and a fall trip which was still rather comfortable - in the 30s. I got another on sale at Target for $60 and my girlfriend and I each used these down to the low 20's this February. We were quite warm (I was too warm) with base layers, fleece top and balaclava, a hand warmer in the foot box for good measure.

It's not a bad bag for the money. I am on the lookout for a bag/quilt that is lighter, however. Things sure go fast in the Gear Swap!

EDIT to include that we were both on mats/pads that provided a sufficient R value.

I picked up one of these (they were called the Kelty Lite Trekker 20* then) last summer for about $80 at Target and have used it on several trips with nights as cold as 17 (I did bring a fleece liner for that night though). On its own for me it is not warm enough for winter but too warm for most summer nights (at low altitude) so it's more of a shoulder season and Sierra Nevada bag. Maybe when I have loads of cash hanging around I'll buy something better\lighter but for the budget minded person this bag is ideal.

"i dont know why i wouldnt just pick up a cats meow for $120-$140 or so"

I can think of a few reasons. The Meow costs more, weighs a quarter pound more and based on my experience with the one that's been hanging in my closet after one use a couple of years ago, it's a true 30 degree bag.

Ive had two with different insulations after reading the reveiws in backpacker years back they were initially fairly warm but lost loft and warmth fast although as I mentioned in another thread maybe if I had been gentler stuffing they might have lasted longer. I'll stick with down Its nice to see a reveiw on a cheaper product but it would be nice to see us get a standard r-value pad based on temp. Thanks Brad for the reveiw

Good article. Many new hikers need a decent lightweight bag but (understandably) don't want to shell out $400, so they end up with giant synthetic bags of dubious quality and warmth. I'll be pointing people at this story -- thanks for making it publicly accessible.

So why was the bag cold on one night?I suggest that maybe the pad was not really good enough for the conditions.

Why would I suggest this? Because on previous nights when it was cold and the bag sufficed, the ground had been a lot warmer to start with, from the warm daytimes. It was only cold on the night after a really cold day. And the author was still cold even with a second and better bag over the top.

I see that on campmor and rei that there's a different version of the bag in a neon green. Is the blue one featured here the older version of the bag? Thanks so much for pointing this bag out, I'm just getting into backpacking and this thing is literally a steal for $80!

It looks like a really nice bag for the price. I think, though, that I'll continue to save up for a Montbell spiral down sleeping bag - I thrash around a lot when I sleep and I find regular (i.e., non-stretchy) bags to be too confining and claustrophobic. Regular sleeping bags make me feel like I'm being held hostage.

This Kelty bag on sale from TheClymb for only $50
on 03/25/2011 11:34:01 MDT

TheClymb by the way has this bag on sale for only $50 right now. If you aren't already a member, you can sign up with this link https://www.theclymb.com/invite-from/mountainwalker (I get a $10 credit to apply to gear when a friend I've invited makes a purchase, at no cost to you. You can also earn the same credit any time you invite a friend and they make their first purchase).

I haven't handled the bag up close, but at this price it's very tempting, even if not your primary bag.

Thanks for the great article, very timely find for a friend who is just getting into backpacking. It's nice to see another good bargain article.

Thanks for your responses! I'm glad this piqued some interest, & hope it helps out more people.

A few comments about the discussion... Field testing a sleeping bag for relative/comparable warmth is an inherently subjective undertaking, so I eliminated as many variables as possible. While realizing that some people on BPL use low-rated R-value sleeping pads, for example, I used the same pads I always do. If I had used a lower-rated pad, I wouldn't have had a good comparative baseline. Also note that there have been some great threads correlating sleeping pad R-value to temperature & sleeping bag rating.

In this one: http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?bo=watch&forum_thread_id=39138

Ken Strayer noted that EN standards for testing at 20*F use an R-5 value pad; by comparison, R-2 for 50*F and R-3 for 40*F. I can't find the post right now, but I seem to recall these numbers being supported in another thread by Mr. Nisley. The point, of course, is that to determine if a manufacturer's rating is accurate, it wouldn't be appropriate to use a lower R-value pad than they use for testing.

The two pads I used for testing were the Thermarest Women's Trail Pro (R-5.1) & Exped DownMat 9 (R-8). The R-8 pad, sufficient for subzero *F temperatures, was the pad I used on the cold-sleeping night in the teens. It was clear that all variables were unchanged except for the daytime/nighttime temperature swing.

For those interested in such things, Casey's calculation on loft can be a good starting point... However, for the numbers to be accurate that calculation assumes that the amount of down is going into the same-cut sleeping bag shell & that the shell fabric is the same weight. Given that the two bags compared have a difference of 3" in shoulder girth, and have different-weight shells, the actual "loft ratio," if we were to call it that, would be more in favor of the Western bag.

All that said, my goal was to emphasize real-world, practical findings... more so "Does it work as advertised" than "What do the specs say," ya know? And hey, the good news is that it DOES work pretty much as advertised. Now if we could just find a $150, sub 3-pound, double wall tent ;)

Excellent review, thank you. I am exactly the guy you are talking about: Just getting into hiking, camping, kayaking, etc. building up my gear slowly, buying a couple items a year.

I was back and forth for about a month on to get this bag or the Kelty lightyear XP 20. My wife got me the XP because I told her I wanted that one, then changed my mind, but she had already ordered it. Lo and behold I was at TJ Maxx this last saturday and picked up the Cosmic 20 for $50! That's $30 less than what campmor wanted. Needless to say I am happy (1) because your review was so enlightening, and (2) I now have two very nice beginner sleeping bags for my wife and I!